Abstract
We examined how the perceived simultaneity and temporal order of two visual stimuli depends upon the depth position of the stimuli specified by binocular disparity cue. When two stimuli were presented simultaneously at different depth positions in front of or around a fixation point, the observer perceived the more distance stimulus appeared before the nearer stimulus (Experiment 1). This illusory temporal order was found only for sudden stimulus presentation (Experiment 2). Similar tendency was found in the processing for motion-in-depth (Experiment 3). For the involuntary attention, which was caused by sudden presentation of a preceding stimulus, the effect of the preceding stimulus, which was presented in the depth space nearer than the fixation point, was larger than that of the stimulus, which was presented in the more distant space than the fixation point (Experiment 4). These results suggest that a common processing, which are related to the detection of the motion-in-depth underlies these bias in terms of the stimulus depth position, and therefore, that, in order to understand the basis of the perception of the simultaneity and temporal order, we have to clarify the temporal bias in the processing which are involved in conducting the experimental task.
